1. Field of the Invention
This invention relates to a light amount adjusting apparatus in an apparatus utilizing a light source which emits pulse light, and for example, to an exposure apparatus using an excimer laser to project a mask pattern onto a semiconductor wafer.
2. Related Background Art
Heretofore, in a reduction projection type exposure apparatus used in the lithography process of the manufacture of integrated circuits, i.e., a so-called stepper, a super-high pressure mercury lamp has been used as a light source for exposure.
This super-high pressure mercury lamp outputs light of plural wavelengths, and with the improvement in the resolving power required in the lithography, the wavelength of the light utilized has become shorter, and not only light of a wavelength of 436 nm but also light of a wavelength of 365 nm has come to be utilized.
However, for any shorter wavelengths, the amount of energy thereof is small and only lithography of very low throughput can be realized.
Attention has recently been paid to excimer laser as a solution to such a problem.